The present invention relates to vitrectomy probes and more particularly, to vitrectomy probes structurally arranged to operate with a reduced level of friction.
Microsurgical procedures frequently require precision cutting and/or removing various body tissues. For example, certain ophthalmic surgical procedures require cutting and removing portions of the vitreous humor, a transparent jelly-like material that fills the posterior segment of the eye. The vitreous humor, or vitreous, is composed of numerous microscopic fibrils that are often attached to the retina. Therefore, cutting and removing the vitreous must be done with great care to avoid traction on the retina, the separation of the retina from the choroid, a retinal tear, or, in the worst case, cutting and removal of the retina itself In particular, delicate operations such as mobile tissue management (e.g. cutting and removal of vitreous near a detached portion of the retina or a retinal tear), vitreous base dissection, and cutting and removal of membranes are particularly difficult.
The use of microsurgical cutting probes in posterior segment ophthalmic surgery is well known. These cutting probes typically include a hollow outer cutting member, a hollow inner cutting member arranged coaxially with and movably disposed within the hollow outer cutting member, and a port extending radially through the outer cutting member near the distal end thereof Vitreous humor and/or membranes are aspirated into the open port, and the inner member is actuated, closing the port. As the port closes, cutting surfaces on both the inner and outer cutting members cooperate to cut the vitreous and/or membranes, and the cut tissue is then aspirated away through the inner cutting member.
Since vitrectomy probes operate by axial oscillation of one cutting member relative to the other, friction generated by or applied against the oscillating components can affect the efficiency and the performance of the vitrectomy probe. For example, friction may affect or even limit the achievable cut rates with a particular vitrectomy probe. Friction results from a number of factors, including contact points between moving and fixed components within the probe. One example of this includes, for example, movement of the inner cutting member and its driving components relative to fluid and pressure seals within the probe.
One known pneumatic probe system that operates in a suitable manner incorporates four o-ring type seals disposed around an axially oscillating inner cutting member and its driving components, introducing some level of restraining friction. In this known system, the driving components include an aspiration motor tube connected to the inner cutting member. The aspiration motor tube extends through and is driven by a pneumatic diaphragm. Because the aspiration tube extends through the diaphragm, four seals are used to seal the different fluid pressure areas of the probe.
Despite the above described probe system, a need still exists for improved vitrectomy probes. In particular, a need exists for vitrectomy probes that are structurally arranged to have increasingly relatively low friction between components that affect the axial displacement of the cutter.
The present disclosure is directed to addressing one or more of the deficiencies in the prior art.